高超声速飞行器上可调天线的设计与实现

When the aircraft is in hypersonic velocity flight state, plasma sheath will be formed outside the aircraft. The existence of the plasma will cause impedance mismatch of the antenna on the aircraft, resulting in the resonance frequency effset and the increase of return loss. Through the numerical prediction of plasma density at different speeds, heights and other conditions, the influence of antenna resonance frequency offset and other performance is further estimated. Considering the parasitic effect of reactance of the components in L-band, the generalized connection network method is used to design and optimize the matching network for completing the antenna impedance tuning in plasma environment. The experimental results show that the input impedance of the antenna can be adjusted by changing the volume of the varactor in the matching network, which can restore the resonant frequency, return loss and communication performance.